CAT 009

CAT-009 — group_by for counters

Field	Value
Severity	info
Confidence	medium
Auto-fix	❌

group_by for counters — Using group_by + map to count elements allocates many arrays. Use Hash with default value or tally.

Bad code

ary.group_by { |x| x }.map { |k, v| [k, v.size] }